Three firefighters are being treated at a specialist burns unit today after a blaze on a ferry at the Port of Dover.

An investigation is under way after they suffered burns to their heads and forearms while tackling the flames in the boiler room of the DFDS service yesterday afternoon.

Seven crew members were also hurt when the blaze broke out on the the Dieppe Seaways vessel berthed at the Eastern Docks at 2.24pm.

A DFDS spokeswoman said: "The Dieppe Seaways is currently suspended from service and DFDS Seaways will be coordinating with the relevant authorities and the Marine Accident and Investigation Branch (MAIB).

"All other DFDS Seaways sailings are running as normal, with a reduced Dover-Calais service.

Passengers were evacuated in the fire on board a ferry at Dover. Picture: @Kent_999s

More than 300 passengers were evacuated as nine engines - and 45 firefighters - were sent to the scene along with specialist units and a dozen ambulances.

Firefighting operations did not finish until 2am. An investigation into the cause of the blaze will be launched by fire chiefs and the Marine Accident Investigation team later today.

Crews had used a range of resources to put out the fire, including cold-cutting gear and foam.

Paramedics treated 10 patients at the scene - five of whom were taken to hospital with burns to their face, arms and hands.

The three firefighters who were injured in a "flashover" were taken to the William Harvey Hospital, Ashford, but have since been transferred to the East Grinstead Hospital where they are receiving treatment for burns to their heads and forearms.

Video: Firefighters at the Port of Dover

South East Coast Ambulance Service sent critical care paramedics along with other medical staff to the scene.

Members of its hazardous areas response team accompanied firefighters into the "hot zone" to assess and treat patients.

All freight was removed from the vessel as firefighters tackled the blaze.

A Port of Dover spokesman said: "The port's priority is the safety of all of its customers and all ferry passengers have been safely disembarked."

Last night, the A20 was gridlocked as ferry passenger traffic combined with rush-hour queues.

Driver John Sheridan, who was stuck on Capel Hill for 45 minutes, said: "There are over 12 ambulances and God knows how many fire engines - some even towing lifeboats."